System, Method, and Apparatus for Graduated Difficulty of Human Response Tests

1. A computer program product comprising a non-transitory computer useable storage medium to store a computer readable program for implementing graduated difficulty for a human response test to differentiate between a human response and a computer response, wherein the computer readable program, when executed on a computer, causes the computer to perform operations comprising: initiating a first human response test with a designated level of difficulty at a source computing device in response to a first test request, wherein the first test request comprises a first source identifier to identify at least one characteristic of the source computing device; recognizing a second test request subsequent to the first test request, wherein the second test request comprises a second source identifier, wherein the second test request occurs after receiving a correct response to the first human response test and after granting requested access of the first test request; initiating a second human response test in response to the second test request, wherein the second human response test has a level of difficulty which is dependent on a determination whether the first and second source identifiers correspond to the same source computing device; and wherein the first human response test is associated with a first difficulty identifier indicative of a first level of difficulty, and the second human response test is associated with a second difficulty identifier indicative of a second level of difficulty, wherein the second level of difficulty is more difficult than the first level of difficulty in response to the determination that the first and second source identifiers correspond to the same source computing device.

2. The computer program product of claim 1 , wherein the operation to initiate the second human response test with the second level of difficulty is further conditioned on a determination that the second test request occurs within a threshold time duration between the first human response test and the second test request.

3. The computer program product of claim 1 , wherein the first and second source identifiers comprise internet protocol (IP) addresses.

4. The computer program product of claim 1 , wherein the first and second human response tests comprise CAPTCHA tests.

5. The computer program product of claim 1 , wherein the computer readable program, when executed on the computer, causes the computer to perform further operations comprising storing the first source identifier in a search identification repository on an electronic storage device in response to implementation of the first human response test.

6. The computer program product of claim 5 , wherein the computer readable program, when executed on the computer, causes the computer to perform further operations comprising using the second source identifier to search the search identification repository to determine whether the second source identifier of the second test request matches the first source identifier of the first test request.

7. The computer program product of claim 1 , wherein the computer readable program, when executed on the computer, causes the computer to perform further operations comprising selecting the second human response test from a plurality of human response tests stored on an electronic storage device, wherein each of the plurality of human response tests stored on the electronic storage device has a corresponding level of difficulty.

8. The computer program product of claim 7 , wherein the computer readable program, when executed on the computer, causes the computer to perform further operations comprising: for each of the plurality of human response tests stored on the electronic storage device, storing the corresponding level of difficulty, wherein the corresponding level of difficulty is derived from statistical data for each of the plurality of human response tests; and selecting the second human response test based on the corresponding level of difficulty associated with the second human response test.

9. The computer program product of claim 1 , wherein the computer readable program, when executed on the computer, causes the computer to perform further operations comprising generating the second human response test on demand with an estimated level of difficulty in response to the second test request and the determination whether the first and second source identifiers correspond to the same source computing device.

10. A server comprising: a network interface to connect the server to a network and to facilitate electronic communications between the server and a client computer coupled to the network; and a test controller coupled to the network interface, wherein the test controller is configured to implement a human response test with a level of difficulty on the client computer in response to an access request by the client computer, wherein the level of difficulty of the human response test is dependent on a determination whether the access request is deemed to originate from a spambot, wherein the human response test occurs after receiving a correct response from a prior human response test from the client computer and after granting requested access of the prior human response test; and wherein the prior human response test is associated with a first difficulty identifier indicative of a first level of difficulty, and the human response test is associated with a second difficulty identifier indicative of a second level of difficulty, wherein the second level of difficulty is more difficult than the first level of difficulty in response to a determination that a first source identifier corresponding to the prior human response test and a second source identifier corresponding to the human response test correspond to a same source computing device.

11. The server of claim 10 , wherein the test controller comprises a spambot tester to determine whether the access request from the client computer originates from the spambot, wherein the spambot tester is configured to compare a source identifier associated with the access request with stored source identifiers associated with previous access requests, and to identify the client computer as a spambot in response to determining that the source identifier associated with the access request matches one of the stored source identifiers.

12. The server of claim 11 , wherein the spambot tester comprises an algorithm stored on a computer readable storage medium, and the spambot tester is further configured to implement the algorithm to determine whether the access request from the client computer occurs within a threshold time duration from a previous access request from the same client computer.

13. The server of claim 12 , further comprising a source identification repository coupled to the test controller, wherein the source identification repository is configured to store the source identifier associated with the access request from the client computer and the source identifiers associated with the previous access requests, as well as access requests timestamps corresponding to each of the stored source identifiers.

14. The server of claim 10 , further comprising a test repository coupled to the test controller, wherein the test repository is configured to store a plurality of human response tests and a corresponding plurality of difficulty indicators to indicate a level of difficulty for each of the stored human response tests.

15. The server of claim 10 , wherein the test controller is further configured to generate the human response test with the level of difficulty for implementation on the client computer in response to the access request by the client computer.

16. A method comprising: initiating a first human response test with a designated level of difficulty at a source computing device in response to a first test request, wherein the source computing device is identifiable by at least one source characteristic; recognizing a second test request from the same source computing device based on identification of the source characteristic, wherein the second test request occurs after receiving a correct response to the first human response test and after granting requested access of the first test request; selecting a second human response test having an increased level of difficulty relative to the level of difficulty of the first human response test in response to recognizing the second test request is from the same source computing device; implementing the second human response test having the increased level of difficulty at the same source computing device; and wherein the first human response test is associated with a first difficulty identifier indicative of a first level of difficulty, and the second human response test is associated with a second difficulty identifier indicative of a second level of difficulty, wherein the second level of difficulty is more difficult than the first level of difficulty in response to the determination that the source characteristics correspond to the same source computing device.

17. The method of claim 16 , further comprising determining whether the second test request occurs within a threshold time duration from the first human response test as a precondition prior to implementing the second human response test with the increased level of difficulty.

18. The method of claim 16 , further comprising determining whether a result of the first human response test is successful as a precondition prior to implementing the second human response test with the increased level of difficulty.

19. The method of claim 16 , further comprising: storing the source characteristic of the source computing device in a search identification repository on an electronic storage device; and storing a plurality of human response tests and corresponding difficulty indicators in a test repository on the electronic storage device.